In modem telecommunication system, transmission method taking time-slot, frame or multiple frames as a unit is popular. In order to transmit data of multiple services simultaneously, it is necessary to combine (to multiplex) data of various services in a certain format at the transmitting end, and to de-multiplex received data of various services with the same format at the receiving end. At transmitting end, combined data and its combination format information are sent simultaneously, and at receiving end, the received data are de-multiplexed according to the received combination format information.
Specially speaking, in present transmission methods of multiple services combination, such as initialization of services between a base station and a mobile, an identical set including all transport formats combination is created at both sides, which is called Transport Format Combination Set (TFCS). When data of services are transported according to certain Transport Format Combination (TFC) at the transmitting end, a Transport Format Combination Indicator (TFCI) is transported simultaneously. The TFC may include multiplex mode, characteristics of the service, such as coding mode, etc. At the receiving end, the TFC of the received data is looked for in the TFCS according to the received TFCI, and then the received data are properly processed based on the TFC.
In order to satisfy requirement of multiple services, TFCI must be updated with certain rate, usually at least once in 10 ms. Therefore, transmission of TFCI occupies a larger part of channel resource. For example, in the TD-SCDMA scheme of CWTS (China Wireless Telecommunication Standard) there are 64 chips for TFCI transmission of each time-slot.